Method of controlling emissions from furnaces

ABSTRACT

This disclosure proposes an improved method of and apparatus for collecting the fumes of industrial furnaces but in particular of steelmaking furnaces which rotate and known in the industry as Basic Oxygen Furnace and Tilting Open-Hearth. But especially this disclosure applies to fume collecting from a furnace having the bottom perforated and employing tuyeres for the introduction of oxygen and other gases through the bottom thereof. This is accomplished by providing a fume collecting hood which is rotatable in conjunction with a blowing furnace in order to accompany the mouth of the furnace and thereby collect its emissions under any angular position of said furnace.

United States Patent [191 Calderon [451 Oct. 29, 1974 METHOD OF CONTROLLING EMISSIONS FROM FURNACES [22] Filed: Apr. 10, 1972 [21] Appl. No.: 242,647

[52] US. Cl. 75/60, 266/31 [51] Int. Cl C2lc 5/28, C2lb 7/08 [58] Field of Search 75/60; 266/31 [56] References Cited UNITED STATES PATENTS 2,584,151 2/1952 Morrison 75/60 3,143,411 8/1964 Hoff 75/60 3,186,831 6/1965 Pike 75/60 3,222,045 12/1965 Spetzler 75/60 3,303,018 2/1967 Goss 75/60 3,423,202 1/1969 Ledune 75/60 3,498,783 3/1970 Johansson 75/60 Primary ExaminerL. Dewayne Rutledge Assistant Examiner-Peter D. Rosenberg 5 7 ABSTRACT This disclosure proposes an improved method of and apparatus for collecting the fumes of industrial furnaces but in particular of steelmaking furnaces which rotate and known in the industry as Basic Oxygen Furnace and Tilting Open-Hearth. But especially this disclosure applies to fume collecting from a furnace having the bottom perforated and employing tuyeres for the introduction of oxygen and other gases through the bottom thereof. This is accomplished by providing a fume collecting hood which is rotatable in conjunction with a blowing furnace in order to accompany the mouth of the furnace and thereby collect its emissions under any angular position of said furnace.

4 Claims, 11 Drawing Figures PATENTED MI 29 $374 3.844.788 smrsr nor 4 SUMMARY OF THE INVENTION The present invention relates to a method of and apparatus for collecting the fumes from industrial furnaces which furnaces are rotatable about an arc or a pivot. More particularly the invention provides a novel method of truly collecting the fumes of rotatable steelmaking furnaces but especially furnaces identified as bottom-blown furnaces employing tuyeres or perforations (not shown) known to the art for over a century. and using oxygen under pressure through said tuyeres for refining. Other gases are also used in conjunction with the oxygen for cooling purposes but this does not comprise part of this invention. In the art of steelmaking the bottom-blown furnace is serviced (charged, tapped, temperature-taking, sample-taking, etc.,) at certain angles hereinafter termed reclined position, while the refining takes place with the furnace substantially in the vertical position and hereinafter termed upright position. The gases blown under pressure through the tuyeres keep the metal from running down into them. However, this type of blowing presents a serious pollution problem because huge flames and smoke are trajected from the furnace. Bessemer furnaces which are not in use nowadays did not have any pollution control system and with the advent of the Basic Oxygen Furnace, known also as top-blown furnace, a fixed hood system was provided to collect the emissions during blowing which takes place only when the furnace is in the upright position, but with the reintroduction of bottom-blown furnaces taking place re cently which furnaces are more efficient than topblown furnaces, a serious pollution problem occurs because blowing takes place both in the reclined position as well as in the upright position. The present invention solves this serious pollution problem and its main object is to provide an effective pollution control system to a rotatable furnace so that fumes are collected while the furnace is blowing in any position, reclined or upri ht.

Another object of the invention is to provide a pollution control system for a bottom-blown furnace which is adapted to revolve and accompany the fume discharge aperture of the furnace at any angle in order to collect its fumes while said furnace is changing position from the reclined to upright or vice versa.

Still another object of the invention is to locate the center of rotation of said pollution control system on the same axis of rotation of the furnace so that this system can circumscribe an arc to follow the arc circumscribed by the furnace aperture through which fumes escape. making it possible to be in registry at all times with the furnace at any angle of rotation.

Yet another object of the invention is to provide a hood means which is water cooled to revolve about an axis of rotation in order to be flexible enough to follow the aperture of the blowing furnace to capture fumes during the servicing portion as well as the refining portion of the cycle of steelmaking.

Further yet, another object of the invention is to provide a skirt to the intake extremity of the hood which skirt can be moved towards and away from the mouth of the furnace to control air infiltration into said hood.

It is another object of the invention to provide a support beyond the hood which is cleviced and yet in line with the center of rotation of the hood in order to minimize cantilevered loadings on the structure of said hood.

Other objects of this invention will appear in the following description and appended claims. Reference is being made to the accompanying drawings forming a part of this specification wherein reference characters designate corresponding parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a bottom blown furnace similar to the Bessemer converter, with the hood of the instant invention disposed over its mouth;

FIG. 2 is a section taken at A-A of FIG. 1 with the hood in the blowing position shown in solid, and in the revolved position shown in phantom;

FIG. 3 shows the charging of molten metal with the hood in position to collect fumes during the charging operation;

FIG. 4 shows the furnace in the reclined position with the hood in registry to collect fumes before it is rotated tits upright blowing position;

FIG. 5 shows the furnace in the upright position with the hood (solid lines) in registry with it, to collect fumes during the refining portion of the cycle;

FIG. 6 shows the furnace in the upright position with the hood having a skirt for controlling air infiltration into the hood during the blowing portion of the cycle;

FIG. 7 is a section taken at A-A of FIG. 6;

FIG. 8 shows the charging of molten metal with the skirted hood in position to collect fumes during chargmg;

FIG. 9 shows the sealing of the fume discharge aperture of the furnace while it is in the reclined position in preparation for rotating it to the upright position at the start or at the end of the blow;

FIG. 10 shows the furnace in the upright position, refining the metal, with the skirt for air infiltration control in position over the fume discharge aperture of the furnace;

FIG. 11 is a diagram showing the hood and the skirt.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1, 20 indicates the rotatable bottom-blown furnace which is pivoted about axis 21; fume discharge aperture, of the furnace is shown by 22. Preferably on the same axis as furnace 20, hood 23 is structured to rotate substantially on the same axis as 21 and noted at 21a. Hood 23 takes the form of an elbow for practical design purposes but it does not necessarily have to have the shape shown. l-Iood 23 which is water cooled is equipped with drive 24 to effect the rotary motion for it. Support 25 having the shape ofa rocker arrangement is furnished for stability. Support 26, pivoted on the same centerline as 21a, by means of clevice 27 adds further stability to hood 23. Drive 28 indicates the revolving motive power for furnace 20; while 29 represents the mouth of the hood which registers with furnace discharge aperture 22 for the collection of the emissions. Box 30 shown in phantom is the chamber to drop the temperature of the gases whence they are ducted to the precipitator (not shown). The fans of the precipitator (also not shown) suck the gases from'furnace aperture 22 and are directed to box 30. Ladle 31, in FIGS. 3 and 8 is shown in the molten metal charging position. Skirt 32 activated by motive power such as cylinders 33, raise and lower skirt 32 in order to control air infiltration between furnace aperture 22 and mouth 29. Flap 34 is provided to enhance the collection of the fumes during charging.

In operation, while using the nonskirted hood arrangement by way of example, the functions are as follows:

Hood 23 is positioned as shown by FIG. 3 and furnace 20 is reclined so that it is serviced such as charged with scrap (not shown) and molten metal by ladle 31. Furnace 20 being reclined, is therefore in the proper position to prevent molten metal from entering the tuyeres. The fumes created by charging are thus sucked up by hood 23 through its mouth 29. During the servicing of furnace 20, such as charging, a slight pressure is maintained in the tuyeres such as blowing nitrogen under pressure to insure the keeping of the tuyeres open. This also is not part of the instant invention. Having charged the furnace, hood 23 rotates so that aperture 21 of furnace 20 is in registry with mouth 29 of hood 23, and the blast of oxygen is blown from the tuyeres pretty much over the charge. A violent reaction immediately ensues, with a tremendous burning gas evolution escaping from aperture 22 and entering directly into mouth 29 of hood 23. The sucking of all the gases is by induced draft from the fans of the precipitator (not shown). Furnace 20 and hood 23 are then simultaneously rotated to the upright blowing position as shown by FIG. to do the refining while preventing fumes to escape because of the registry and accompaniment of hood 23 during the rotation of furnace 20.

In employing skirted hood 23 as shown by FIG. 8 during the charging part of the cycle, the emissions from ladle 31 and furnace 20 are sucked through flap 34 and skirt 32. The charging completed, hood 23 assumes the position as shown by FIG. 9 and skirt 32 is moved toward aperture 22 of furnace 20 to control air infiltration. The blast through the tuyeres begins and both hood 23 and furnace 20 are simultaneously rotated to the upright position as shown by FIG. thereby preventing any emission to take place out of furnace during rotation from the reclined to the upright position. At all times. molten metal is kept from entering the tuyere by the pressure of the gases being blown through them.

During the blowing of oxygen, refining of the steel takes place. In taking temperature and samples from furnace 20, both hood 23 and furnace 20 are rotated simultaneously to the reclining position shown by FIGS. 9 and 4, and the blast of oxygen shut-off. Hood 23, with skirt 32 unsealing aperture 22, is then independently rotated to a position which is close to the position shown for charging, and samples as well as temperv and in particular bottom-blown furnaces. While pre-' ferred embodiments of the present invention have been illustrated and described in considerable detail, the invention is not to be considered limited to the precise constructions shown. It is intended to cover hereby all adaptations, modifications and used of the invention which come within the scope of the appended claims.

What is claimed is:

l. A method of refining metal in a bottom-blown furnace and controlling emissions from the furnace comprising:

a. providing a bottom-blown furnace defining a charge cavity having a furnace mouth and flow passages through which gas is directed into said cavity;

b. charging said furnace by introducing a molten metal into the cavity via said mouth when said furnace is in a charging position with said flow passages above the level of metal in the cavity;

c. moving said furnace to a refining position wherein said flow passages are disposed below the level of the molten charge;

d. directing gas through said passages while moving said furnace;

e. providing an emission receiving hood comprising a tubular hood body having an emission receiving opening therein;

f. aligning said hood opening with said furnace mouth after said furnace is charged;

g. moving said hood body while moving said furnace to maintain said emission receiving opening adjacent and aligned with said furnace mouth;

h. maintaining said emission receiving opening aligned with an adjacent said furnace mouth while said furnace is in its refining position;

i. moving said furnace away from the refining position to a tapping or a sample taking position; and,

j. maintaining said emission receiving opening aligned with and adjacent said furnace mouth while moving said furnace from said refining position.

2. A method as claimed in claim 1 wherein moving said furnace comprises rotating said furnace about an axis to move said mouth along a path of travel defining an are about said axis.

3. A method as claimed in claim 2 wherein moving said hood comprises rotating said hood about said axis to move said emission receiving opening in a second path of travel defining a second arc about said axis, said first and second paths of travel extending radially adjacent each other.

4..A method as claimed in claim 1 further comprising providing a movable skirt extending about one of said furnace mouth or emission receiving opening and moving said skirt when said mouth is aligned with said emission receiving opening to define a flow passageway extending between said mouth and said emission receivgi s a a a a 

1. A METHOD OF REFINING METAL IN A BOTTOM-BLOWN FURNACE AND CONTROLLING EMISSIONS FROM THE FURNACE COMPRISING: A. PROVIDING A BOTTOM-BLOWN FURNACE DEFINING A CHARGE CAVITY HAVING A FURNACE MOUTH AND FLOW PASSAGES THROUGH B. CHARGING SAID FURNACE BY INTRODUCING A MOLTEN METAL INTO THE CAVITY VIA SAID MOUTH WHEN SAID FURNACE IS IN A CHARGING POSITION WITH SAID FLOW PASSAGES ABOVE THE LEVEL OF METAL IN THE CAVITY; C. MOVING SAID FURNACE TO A REFINING POSITION WHEREIN SAID FLOW PASSAGES ARE DISPOSED BELOW THE LEVEL OF THE MOLTEN CHARGE; D. DIRECTING GAS THROUGH SAID PASSAGES WHILE MOVING SAID FURNACE; E. PROVIDING AN EMISSION RECEIVING HOOD COMRPISING A TUBULAR HOOD BODY HAVING AN EMISSION RECEIVING OPENING THEREIN; F. ALIGINING SAID HOOD WITH SAID FURNACE MOUTH AFTER SAID FURNACE IS CHARGED; G. MOVING SAID HOOD BODY WHILE MOVING SAID FURNACE TO MAINTAIN SAID EMISSION RECEIVING OPENING ADJACENT AND ALIGNED WITH SAID FURNACE MOUTH; H. MAINTAINING SAID EMISSION RECEIVING OPENING ALIGNED WITH AN ADJACENT SAID FURNACE MOUTH WHILE SAID FURNACE IS IN ITS REFINING POSITION. I. MOVING SAID FURNACE AWAY FROM THE REFINING POSITION TO A TAPPING OR A SAMPLE TAKING POSITION; AND, J. MAINTAINING SAID EMISSION RECEIVING OPENING ALIGNED WITH AND ADJACENT SAID FURNACE MOUTH WHILE MOVING SAID FURNACE SAID REFINING POSITION.
 2. A method as claimed in claim 1 wherein moving said furnace comprises rotating said furnace about an axis to move said mouth along a path of travel defining an arc about said axis.
 3. A method as claimed in claim 2 wherein moving said hood comprises rotating said hood about said axis to move said emission receiving opening in a second path of travel defining a second arc about said axis, said first and second paths of travel extending radially adjacent each other.
 4. A method as claimed in claim 1 further comprising providing a movable skirt extending about one of said furnace mouth or emission receiving opening and moving said skirt when said mouth is aligned with said emission receiving opening to define a flow passageway extending between said mouth and said emission receiving opening. 